Javad JNSGyro-4T, Operator'S Manual

Page: 47 / 116

www.javad.com JNSGyro-4T Operator’s Manual 2-17
C O N F I G U R A T I O N
Collecting Almanacs
Collecting Almanacs
Each satellite broadcasts message (almanac) which gives the approximate orbit
for itself and all other satellites. If the unit has an almanac, you can considerably
reduce the time needed to search for and lock on to satellite signals.
The JNSGyro-4T regularly updates the almanac and stores the most recent
almanac in boards’ Non-Volatile Random Access Memory (NVRAM).
1.
Set up the JNSGyro-4T (connect the external antennas if needed) in a
location with a clear view of the sky.
2.
Turn on the JNSGyro-4T. Wait for about 15 minutes while the unit collects
almanac data from satellites.
Notice: If 15 minutes have passed and the JNSGyro-4T does not
lock on to satellites, you may need to clear the NVRAM.
See “Clearing the NVRAM” on page 4-16 for this
procedure.
You will need to collect or update the almanac:
• If the JNSGyro-4T has been off for a long time.
• If the last known JNSGyro-4T position, stored in the boards’ NVRAM, is
different from the present position by a few hundred kilometers at least.
• After loading new OAFs.
• After loading new firmware.
• After clearing the boards’ NVRAM.
• Before measuring.
The collection and/or update of an almanac can take as long as 15 minutes.